Microstructural evolution of René N4 during high temperature creep and aging

[Display omitted] •René N4 microstructural evolution is fundamental to derive models able to predict service conditions of components through microstructural analysis.•Microstructural parameters w and λ and their variation from virgin condition were measured on some creep and statically damaged specimens.•After all tests performed, Δλ shows a good repeatability and clear independence on the stress applied.•Differently from what stated in literature for other superalloys, Δw does not show a direct dependence on the stress applied in René N4.•Δλ could be the right parameter to describe microstructural evolution of René N4 in function of service time and temperature. The main scope of this work is to describe the microstructure evolution of single-crystal (SX) superalloy René N4 during creep and static aging at high temperatures, in function of time, stress and temperature. During creep at high temperatures, SX microstructure evolves from a dense and ordered distribution of cuboidal γ′ particles to a configuration characterized by alternate rafts of γ′ phase and γ matrix, through a process known as rafting. The microstructural evolution of superalloys is very important to derive models able to predict service conditions of a component through microstructural analysis. In this work two microstructural parameters were identified and analyzed for René N4: matrix channels width w along the [001] lattice direction and periodicity width λ, given by the sum of w and the width of the γ′ precipitates along [001]. Both parameters were measured on some creep-damaged and some statically aged specimens, as well as on the virgin material to analyze their trends in function of time, temperature and stress. In particular, the parameter Δλ looks independent of both the stress level and the microstructural morphology and could be used in future works to develop microstructural evolution model of René N4 in function of service time and temperature.